Report the birth of your daughter ASAP to the American Embassy. I don't know what is involved, but sooner the better.
If you don't like to go through long processes, you'll have to say goodbye to US citizenship for your daughter. Let alone what is involved in the report of birth and passport issue for your daughter right now, she as a foreign-born US citizen will have to go through a process quite similar to naturalization of a foreign national when she arrives in the US to finalize her US citizenship. I know this is true because a couple of my friends did, and so did the kids of my friends.